Mixing devices and assemblies are in wide use in industry, for example, in the food processing, pharmaceutical, biotechnology, chemical, consumer product manufacturing, and other industries. In these industries, it is often desirable to contain a material to be mixed or agitated such as, for example, a liquid, a slurry, or any other material in a vessel and to impart mixing or agitating energy to the material via a shaft that is driven to rotate and has axially extending impellers that impart force to the material. The impellers often take the form of flat or curved blades.
One recently developed type of such mixer, which is sometimes especially suitable for industries requiring very high sanitary or cleanliness or cleanability conditions, is a so-called magnetically driven mixer arrangement.
In one type of a magnetically driven mixer arrangement, the material to be mixed or agitated is sealed inside a vessel and a bearing housing which supports the impeller shaft is provided adjacent an opening of the vessel. The end of the impeller shaft housing is closed with a domed-shape canister. Inside the canister, the end of the impeller shaft has an inner magnetic rotor, which is typically a rotor or a shaft stub having magnets disposed thereon.
External to the canister, a drive system is provided which has a hollowed out outer magnetic rotor which fits around and over the canister, and also has magnets disposed thereon. The outer magnetic rotor is driven by a motor and gear box with an associated shaft, all external to the canister and to the mixing vessel. Typically, the inner rotor magnets face outwardly towards the canister. Also, typically the outer rotor magnets face inwardly towards the canister. Rotation of the outer magnetic rotor creates a rotating magnetic field that tends to rotate the inner magnetic rotor, thus driving the impeller shaft.
In many magnetically driven mixer systems, it has been a prior practice to semi-permanently affix the drive system to the bearing housing by utilizing radially extending flanges having holes in the flanges combined with bolts through the holes of the associated flanges.
This type of arrangement uses radial flanges and axial bolts and provides good alignment and durability. However, this arrangement also has the disadvantage that it is relatively cumbersome and time consuming to undo all of the bolts in order to remove the motor and drive assembly from the bearing housing. This is especially true since a relatively large number of bolts can be involved. Of course reinstalling the drive system to a vessel also requires a cumbersome and time consuming operation of a fairly large number of bolts.
In the case of most known prior art systems, this has not posed a significant disadvantage, because the only removal of the motor and drive system that occurs would occur during some kind of cleaning or servicing of the bearing housing which does not occur particularly frequently. Also, since the bearing housing is detachable from the opening in the vessel, it has been a suitable practice to detach the bearing housing and motor drive assembly as one single unit.
However, in some instances it would be desirable to have a more readily detachable and re-attachable drive system. Accordingly, there is a need in the art for a mixing impeller drive system and method that provides a convenient, economical and rapid installation and removal of the drive system from the remainder of the mixer assembly.